European rabbits were introduced to Australia in 1859. The rabbits reproduced rapidly in their new environment, displaced other animals and overgrazed vegetation. In an attempt to reduce the rabbit population, a deadly virus was introduced in 1951. When the virus was first introduced, the rabbits died in large numbers, but the death rate decreased over time. What statement best explains the decrease in the rabbit death rate? A) The virus had a short life span and died out with the rabbits. B) Natural selection favored rabbits that were resistant to the virus. C) The rabbits died of natural causes and the introduced virus did not work. D) Young rabbits exhibited a learned behavior and began to avoid being infected by the virus.

Answers

Answer 1

Answer:

B) Natural selection favored rabbits that were resistant to the virus

Explanation:

Most likely, virus resistance occurred over time, as a consequence of mutation. Individuals that carried the resistance mutation become favourable by natural selection.

Natural selection is evolutionary mechanism which favours traits of an organism that help him survive and reproduce (increase organism's fitness). In the example above, resistant rabbits that survived had the favorable trait (resistance) by natural selection.

Answer 2

Final answer:

The decrease in the rabbit death rate is best explained by natural selection, which favored rabbits that were genetically resistant to the virus, leading them to survive, reproduce, and pass on their resistance to their offspring.

Explanation:

The statement that best explains the decrease in the rabbit death rate after the introduction of a deadly virus in Australia in 1951 is B) Natural selection favored rabbits that were resistant to the virus. As the virus killed a large number of the rabbit population, those few rabbits that had some natural resistance to the virus were more likely to survive and reproduce. Over time, the offspring of these resistant rabbits would inherit this resistance, leading to a population of rabbits that were less affected by the virus and therefore a decrease in the death rate among the rabbit population as a whole. This process is a clear example of natural selection at work, where a beneficial trait - in this case, resistance to the virus - becomes more common in the population over time because it confers a survival advantage.


Related Questions

What characteristic of the subunits allows for a uniform diameter of the double helix?

Answers

The diameter of the DNA double helix is uniform throughout because a purine (two rings) always pairs with a pyrimidine (one ring) and their combined lengths are always equal.

Final answer:

The uniform diameter of the DNA double helix is due to the base pairing between purine and pyrimidine bases, which each occupy the same amount of space, resulting in a consistent structure with a diameter of 2 nm.

Explanation:

The characteristic of the subunits that allows for a uniform diameter of the double helix in DNA is the base pairing between a purine and a pyrimidine. DNA comprises two anti-parallel strands twisted around each other, with the purine bases (adenine and guanine) pairing with the pyrimidine bases (thymine and cytosine) in the opposing strand. This pairing is stabilized by hydrogen bonds; adenine pairs with thymine via two hydrogen bonds, while guanine pairs with cytosine via three hydrogen bonds. The purine and pyrimidine bases pair so that the DNA strands form a double helix with a uniform diameter of 2 nm. These base pairs each take up the same amount of space and create a regular pattern of major and minor grooves along the DNA molecule, which assists in binding proteins to the DNA.

in humans, widow peaks are dominant to straight hairlines and freckles are dominant to no freckles. A woman who is homozygous for her widow's peak and heterozygous for freckles marries a man that has a straight hairline and is also heterozygous for freckles. Determine the phenotypic ratio. What is the probability that they have a child who looks like dad?

Answers

Final answer:

Using Punnett squares for the genetics of widow's peaks and freckles, the offspring will all have widow's peaks (due to dominance and mother's homozygous genes) and a 3:1 ratio of having freckles to not. The chance that a child will completely resemble the father is 0.

Explanation:

The question revolves around genetics and Punnett squares to determine possible offspring traits. Traits such as widow's peaks and freckles are controlled by genes. In this scenario, widow's peaks and freckles are dominant traits, while straight hairline and no freckles are recessive. The woman's genetic makeup for the traits is (WW, Ff), while the man's is (ww, Ff).

A Punnett square shows all possible combinations of offspring from these parents. For the widow's peak, all offspring will have at least one W allele, so all will have widow's peaks. The freckle trait, however, can be FF, Ff, or ff. The phenotypic ratio of the offspring is: 1 widow's peak: 0 straight hairline and 3 Freckles: 1 no freckle.

To look like the father (straight hairline, freckles), the child would need the wwFf combination. However, as the mother is homozygous for the widow's peak (WW), none of the offspring can have a straight hairline. Therefore, the probability they have a child who entirely looks like the dad (straight hairline, freckles) is 0.

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According to the question,

The phenotypic ratio of their offspring is 1:1 for widow's peak and freckles to widow's peak and no freckles.The probability that they have a child who looks like the dad (with a straight hairline and freckles) is 1/8.

To determine the phenotypic ratio of their potential offspring, let's first identify the possible combinations of alleles for each trait:

For the widow's peak trait:

Woman (homozygous for widow's peak): WWMan (straight hairline): ww

For the freckles trait:

Woman (heterozygous for freckles): FfMan (heterozygous for freckles): Ff

Now, let's combine these alleles to determine the possible genotypes of their offspring:

For the widow's peak trait:

Offspring: Ww (heterozygous for widow's peak)

For the freckles trait:

Offspring: FF, Ff, or ff (homozygous dominant for freckles, heterozygous for freckles, or homozygous recessive for no freckles)

Now, let's cross these genotypes to find the phenotypic ratio:

Widow's peak : Straight hairline = 1:1

Freckles: No freckles = 3:1 (1 FF : 2 Ff : 1 ff)

So, the overall phenotypic ratio of their potential offspring is 1:1 for widow's peak and straight hairline, and 3:1 for freckles to no freckles.

Now, to find the probability that they have a child who looks like the dad (straight hairline and no freckles), we need to look at the combination of traits that match the father:

For straight hairline: 1/2 (since the father is homozygous recessive for straight hairline)

For no freckles: 1/4 (since the father is heterozygous for freckles)

So, the probability that they have a child who looks like the dad (both straight hairline and no freckles) is the product of these probabilities:

Probability = (1/2) * (1/4) = 1/8

Therefore, there is a 1 in 8 chance that they have a child who looks like the dad.

Changing a single amino acid in a protein consisting of 433 amino acids would

Answers

Hey there! :D

Changing amino acids in a protein of 433 amino acids would change the entire protein. It would no longer be the same. It depends on where the protein is affected, the first sequence, or the last one. One wrong nucleotide leading to a wrong amino acid affects the whole chain and destroys the proteins natrual purpose.

I hope this helps!

~kaikers

Final answer:

Changing a single amino acid in a protein can significantly alter the function and structure of the protein. This is demonstrated in medical conditions such as sickle cell anemia, where a single amino acid substitution affects the entire protein function.

Explanation:

Changing a single amino acid in a protein consisting of 433 amino acids can indeed have a substantial effect on the structure and function of the protein, as the functional properties of a protein are determined by its specific sequence of amino acids. For instance, in the case of sickle cell anemia, a single substitution of the amino acid glutamic acid with valine in the hemoglobin molecule changes its structure, leading to a different shape of red blood cells and subsequently a dramatic decrease in life expectancy. The unique sequence for every protein is ultimately determined by the gene encoding it. Gene mutations such as substitution, deletion or insertions can cause such changes in the amino acid sequence, resulting either in minor differences in the protein or tangibly altering its function. For example, frameshift mutations caused by insertions or deletions of a number of nucleotides can change every amino acid after the point of the mutation, possibly including a stop codon before the end of the coding sequence, rendering the resulting protein nearly always nonfunctional.

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How many different alleles are possible? Why?

Answers

For humans, we have 19,000 protein-coding genomes. For every gene, there are 2 alleles. This means that humans have 38,000 alleles (19,000×2=38,000).

Which statements about the cycle of weathering, erosion, and deposition are true? Check al that apply.


A. Deposition leads to the breakdown of mountains.


B. Erosion occurs even when mountains are forming.


C. Gravity does not affect the rate of erosion.


D. When new mountains or plateaus form, the cycle starts over.


E. Weathering, erosion, and deposition have almost leveled Earth’s surface.

Answers

Answer:

B,D and E

Explanation:

Final answer:

The true statements about the cycle of weathering, erosion, and deposition include erosion occurring even during mountain formation, the cycle restarting with the formation of new geological features, and these processes contributing to the leveling of Earth's surface over geologic time. Deposition does not break down mountains, and gravity does affect erosion rates.

Explanation:

The cycle of weathering, erosion, and deposition plays a critical role in shaping the landscape. Here are the true statements:

B. Erosion occurs even when mountains are forming. Despite ongoing mountain formation, various erosive forces such as water, wind, and ice continue to wear down these structures.

D. When new mountains or plateaus form, the cycle starts over. The formation of new geological features such as mountains and plateaus triggers the continuation of this natural cycle.

E. Weathering, erosion, and deposition have almost leveled Earth’s surface. Over geologic time scales, these processes have contributed to the leveling of Earth's surface, though mountains and other features still exist due to ongoing tectonic activity.

As for the false statements:

A. Deposition does not lead to the breakdown of mountains; it is a process where materials are laid down or added to a landform.

C. Gravity significantly affects the rate of erosion, as it can influence how quickly and in what direction materials are moved.

PLEASE HELP! BRAINLIEST! Which of the following is used as evidence in supporting the idea that life changes over time?

A. the time period in which an embryo develops

B. the similarities in the body systems such as the nervous and circulatory systems

C. the existence of homologous structure

D. the big bang theory

Answers

The answer would be C

Suppose some natural disaster occurs and a species of finch is forced to relocate from its original island where it dined on cactus flowers to an adjacent island with many fewer cacti but an overabundance of orchids. What would be the immediate consequences to the species in the first month of the change?

A. The species would change its eating habits to feed on orchids.
B. All of the members of the species would make do with the existing cacti on their new island.
C. The entire species would go extinct.
D. Most of the members of the species would die but some would survive.

Answers

Answer

A.The species would change its eating habits to feed on orchids.

Explanation:

The species knows that if they don't make do with what they have, they will go extinct. So they adapt to the new changes. Mark me brainliest please!

Using the model provided, which statement would not be correct regarding ATP?


A) The hydrolysis of ATP to ADP is reversible.


B) When a phosphate group is removed from ATP, ADP is produced and energy is provided for cellular processes.


Eliminate


C) When phosphate is added to ADP, free energy from food sources is stored in the phosphate bond, producing ATP.


D) When a phosphate group is removed from ATP by hydrolysis, ADP is produced and energy is stored for cellular processes.

Answers

Answer:

 D.)

When a phosphate group is removed from ATP by hydrolysis, ADP is produced and energy is stored for cellular processes.

Explanation:

Answer: I also think the answer is D).

Homeostatic regulation completes one cycle, then is done.


1) True


2) False

Answers

False!

Homeostasis is consistently at work in the body. This is because our external environment is always changing and our internal environment (aka our organs) needs to accomodate

Hope this helped!

~Just a girl in love with Shawn Mendes

Assume that in a small population, 15 percent of the people are blue-eyed and have brown hair. Assume further that within this population, there is an adventurous group that wishes to explore the region and settle down in new territory. Of this adventurous group, 87 percent are blue-eyed and have brown hair. When they leave, the gene frequencies in the remaining population will change for blue-eyes and brown hair in the next generation. This is an example of

Answers

Answer:

Natural selection

Explanation:

this is what the example would be

When they leave, the gene frequencies in the remaining population will change for blue-eyes and brown hair in the next generation. This is an example of genetic drift.

What is genetic drift?

Genetic drift is the arbitrary change in the population's frequency of a gene variant that already exists. Gene variations may totally vanish due to genetic drift, which would limit genetic diversity.

Additionally, it can make previously uncommon alleles far more common and even fixed.

Genetic drift occurs when the frequency of different alleles, or variable forms of a gene, fluctuates over time through chance. Changes in allele frequencies are used to measure these differences in allele presence.

Genetic drift, also known as genetic sampling error or the Sewall Wright effect, is an entirely random shift in the gene pool of a small population.

Thus, this is an illustration of genetic drift.

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Which of the following brings amino acids to the ribosome for use in translation?A rRNA (ribosomal RNA)B tRNA (transfer RNA)C mRNA (messenger RNA)

Answers

Answer:

mRNA

Explanation:

Answer:

I THINK its mRNA because i know it isnt a

Explanation:

have a great day

What is the process by which bacteria remove nitrogen from the air and make it available to plants?

Answers

It’s called Nitrogen fixation

Which term describes body parts of different organisms that are similar in form?

A. homologous structures

B. homologous pairs

C. ancestral pairs

D. analogous structures

Answers

Answer:

A. homologous structures

Explanation:

The answer is homologous structures.

A male cat and a male dog both have masculine penile structures.

They are are two different organisms, but the two penises are in a similar form because they are both penises.

Same Structures = Homo Structures

Same with any other parts

Final answer:

A. Homologous structures are body parts in different organisms that are similar because they were inherited from a common ancestor, and they help researchers study evolutionary relationships.

Explanation:

The term that describes body parts of different organisms that are similar in form is homologous structures. These structures are indicative of a common evolutionary ancestor and share a similar embryonic origin. Comparative anatomy studies these homologous structures to understand evolutionary relationships. For example, the bone structure in a whale's flipper is homologous to the bones in a human arm, although their functions are different.

On the other hand, analogous structures represent similar traits due to environmental pressures and convergence rather than a common ancestor. It's important to distinguish if a similarity is due to homology or analogy when studying the phylogeny of different species.

How is it possible that regions thousands of base pairs from a promoter can impact transcription of that gene?

Answers

Answer:

DNA can make loops

Explanation:

Transcriptional factors (such as activators or repressors) are proteins that regulate gene expression by binding to DNA sequence (such as enhancers and silencers). Consequently, gene transcription might be turned on or off. Usually binding sites for transcriptional factors are located near the promoter (initiation of transcription). But when they are located far from the gene they regulate DNA, flexibility plays a role. DNA can form loops which bring together binding sites and transcription factors.

mutation cause a protein to be synthesized with one incorrect amino acid?

Answers

Answer:

A mutation that causes incorporation of an incorrect amino acid in a synthesizing protein is known as missense mutation.

Explanation:

Because of the protein that this amino acid would be carrying.

Answer:

The correct answer will be- Missense mutation

Explanation:

A missense mutation is a type of mutation which takes place due to the change in the single base pair nucleotide caused by the substitution of a different nucleotide.

The change in the single nucleotide leads to change in the codon read during the translation. This change in the codon causes the substitution of a different amino acid which could result in a different protein.  

Thus, missense mutation is the correct answer.

The Joshua Tree in the Mojave Desert: this is an example of a(n) __________ species that is confined to a certain region or having a comparatively restricted distribution. A) endemic B) indicator C) native D) umbrellaThe Joshua Tree in the Mojave Desert: this is an example of a(n) __________ species that is confined to a certain region or having a comparatively restricted distribution. A) endemic B) indicator C) native D) umbrella

Answers

Answer:

A) endemic

Explanation:

Mojave desert is the most driest desert present in North America, as the area is very hot and dry so the flora of that area has adapted to the hot environment, Joshua tree is the endemic species of that region, it exists only in that particular geographic region.

Endemic species are those species of plants and animals that is present in that particular geographic region, a species can be endemic to a continent or a part of continent, means endemic to small or large area. Joshua tree is in the same manner endemic to Mojave desert with somehow restricted distribution.

Answer: the answer is A) endemic

Explanation:

Complete the sentence to describe the similarities and differences between amylose and cellulose. Match the words to the appropriate blanks in the sentences on the right. Be certain each sentence is complete before submitting your answer. D-glucose | D-fructose | L-glucose | B-1,6-glycosidic | a-1,4-glycosidic | a-1.6-glycosidic | B-1,4-glycosidic | a branched | an unbrached | L-fructoseAmylose is _____ chain of _________ units connected by _________ bonds. Cellulose is _________ chain of _________ units connected by _________ bonds.

Answers

Answer:

Amylose is an unbrached chain of D-glucose units connected by a-1,4-glycosidic bonds.  

Cellulose is chain of D-fructose units connected by | B-1,4-glycosidic bonds.

Explanation:

Both, amylose and cellulose are polysaccharides, meaning that they consist of a large number of monosaccharide units. Alo, both form linear structures composed of D-glucose. Differences in those two sugars are that amylose is storage molecule in which glucose unit are connected with α-(1, 4)-glycosidic bond, while cellulose is a structural molecule in which glucose units are linked with β (1, 4) glycosidic bonds.

Amylose is component of starch. Cellulose is the main component of the plants' cell wall.

Assuming that the N-terminal ends of polypeptides were never removed, what would be the first (N-terminal) amino acid in every polypeptide?MethionineArginineLysineAUG

Answers

Answer:

AUG

Explanation:

AUG is the start codon of every amino acid chain.

Most carbon dioxide is transported within blood plasma as

Answers

Answer:

Some of the carbon dioxide is transported dissolved in the plasma. Some carbon dioxide is transported as carbaminohemoglobin. However, most carbon dioxide is transported as bicarbonate. As blood flows through the tissues, carbon dioxide diffuses into red blood cells, where it is converted into bicarbonate.

Explanation:

Final answer:

The majority of carbon dioxide is transported within the blood plasma as bicarbonate. It's part of a process involving carbon dioxide combining with water to form carbonic acid, which rapidly transforms into bicarbonate and hydrogen ions. At the lungs, this process reverses, and the carbon dioxide is exhaled.

Explanation:

Carbon dioxide is primarily transported within the blood plasma as bicarbonate (HCO3-). Carbon dioxide can be transported within the blood via three mechanisms. Firstly, a small fraction (about 5 to 7 percent) of it is dissolved directly into the blood. Secondly, some carbon dioxide binds to hemoglobin or plasma proteins to create carbaminohemoglobin; this accounts for about 10 percent of the transport. The majority of the carbon dioxide (about 70 to 90 percent), however, is transported as bicarbonate within the blood plasma. This is a part of the bicarbonate buffer system.

Inside the red blood cells, carbon dioxide combines with water to produce carbonic acid (H2CO3) through the presence of an enzyme called carbonic anhydrase. This carbonic acid rapidly dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). The bicarbonate ions then get transported out of the red blood cells into the plasma.

At the lungs, this reaction is reversed. The bicarbonate ions move back into the red blood cells where they combine with hydrogen ions to form carbonic acid once again. This is then converted back to water and carbon dioxide, which is eventually exhaled out.

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In his study with pea plants, Mendel studied how short and tall the offspring were after crossing the purebreds. This would be an example of a:
a) Dihybrid cross
b) Trihybrid cross
c) Monohybrid cross
d) Both a and c answers are correct.

Answers

Answer: The answer is C, a monohybrid cross.

Explanation:

A dihybrid cross would be crossing 2 (usually linked) traits in the same punnett square, while a trihybrid cross is with 3 traits. Since he's only studying 1 trait (tall vs. short) the answer is C, a monohybrid cross.

Mendel's experiments with pea plants focusing on a single trait are examples of monohybrid crosses. In these, he crossed two purebred plants differing in one trait, observing dominant and recessive patterns. Hence, the correct answer is c) Monohybrid cross.

In his study with pea plants, Mendel primarily examined single characteristics, such as plant height (short vs. tall), through controlled breeding experiments. This type of experiment, where two purebred individuals with different forms of a single characteristic are crossed, is known as a monohybrid cross. Therefore, the correct answer to the question is: c) Monohybrid cross

In a monohybrid cross, Mendel observed that when he crossed two purebred plants differing in one trait (e.g., tall vs. short), the resulting F1 generation all showed the dominant trait (e.g., tall). When these F1 hybrids were self-pollinated, the recessive trait reappeared in a 3:1 ratio in the F2 generation.

To summarize, Mendel's initial experiments that focused on one trait at a time, such as plant height, exemplify a monohybrid cross, fundamental for understanding basic inheritance patterns.

How does amino acid structure relate to the overall shape of a protein?

Answers

Answer:

A)

Explanation:

Amino acid properties influence the folding and shape of proteins, which determine function. The primary structure of amino acids guides the development of higher-level structures and thus protein shape. Changes in amino acid sequence can alter protein function.

The structure of an amino acid is crucial in determining the overall shape of a protein, which in turn dictates the protein's function. Amino acids have unique properties of size, charge, shape, and acidity that influence their ability to interact with one another. When amino acids link together to form a protein, these interactions lead to the protein's complex three-dimensional structure comprising primary, secondary, tertiary, and sometimes quaternary levels.

Protein synthesis begins with the linear sequence of amino acids, known as the primary structure. As the protein is synthesized, sections of this chain fold locally into patterns like alpha-helices or beta-pleated sheets, forming the secondary structure. This folding brings distant amino acids closer together. Furthermore, the tertiary structure emerges when R-groups or side chains of amino acids interact, leading to the mature three-dimensional shape of the protein.

The primary structure of a protein, determined by the sequence of amino acids, guides this entire process. Changes in the amino acid sequence can lead to alterations in the protein's shape, which may compromise its function. This is partly because the properties of amino acids affect how they bond with one another, with factors like charge and polarity playing a significant role in their interactions.

Proteins are polymers of _____. hydrocarbons amino acids CH2O units glycerol nucleotides

Answers

Hey there! :D

If you ever learned about protein synthesis, you probably have heard about how it is made with amino acids. Messenger RNA (a portion of DNA in the nucleus) is taken to the ribosomes (which make the protein) and the code from the DNA is converted to amino acid sequences, therefore, the polymer and correct answer is amino acid. These amino acids, all combined, become protein chains. I would encourage you to look into the process because it is very interesting and very helpful!

I hope this helps!

~kaikers

Proteins are polymers of amino acids. Proteins are large, complex molecules that play essential roles in almost all biological processes.

Proteins are polymers, which means they are composed of repeating units called monomers. In the case of proteins, the monomers are amino acids.

Amino acids are organic compounds consisting of a central carbon atom bonded to an amino group (NH₂), a carboxyl group (COOH), a hydrogen atom, and a unique side chain or "R" group. There are 20 different amino acids commonly found in proteins, each with a different side chain, giving them unique chemical properties.

During protein synthesis, amino acids are linked together through peptide bonds, which form between the carboxyl group of one amino acid and the amino group of another. This process results in the formation of a linear chain of amino acids, known as a polypeptide chain.

The sequence and arrangement of amino acids in a polypeptide chain determine the protein's structure and function. Proteins can have various levels of structural organization, including primary, secondary, tertiary, and quaternary structures, all of which contribute to their specific biological functions.

Proteins are involved in numerous vital functions within cells, such as enzymatic reactions, cell signaling, transport of molecules, structural support, and immune responses. They are the workhorses of the cell, carrying out a diverse range of tasks critical for the survival and functioning of living organisms. Understanding the structure and function of proteins is central to many areas of biology, biochemistry, and medicine.

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From which of the following are the other
three eukaryotic kingdoms thought to have evolved?
A.) Eubacteria
B.) Protista
C.) Fungi
D.) Plantae

Answers

B. Protista

Bcoz in kingdom protista

Euglenoids and slime moulds are present - having characteristics of both plants and animals..

And protozoans are also present-primituve relatives of animals.

The answer is B. Protista

Flower cluster whose name can be read as a challenge

Answers

Do ya wanna comment so I can understand more of the question

What role has mass extinction played in animal evolution?

Answers

The mass extinctions have had detrimental role when it comes to the evolutionary patters and which organisms prosper, and on the other side which ones are gone forever. There have been numerous extinctions, some being much more extreme than others, but nonetheless they have all reshaped the ''playing ground'' for the organisms. Before a mass extinction occurs, there are lot of species living on land and in water, dominating the Earth by holding the highest niches in the food chain hierarchy, stopping other organisms to develop further as well. Then a mass extinction occurs, be it because of dramatic climate changes, impact with asteroid or comet, intense supervolcano activities, and those sudden changes manage to destroy big portion of the living organisms, with the ones that have been the largest and dominant usually being the most affected. That opens up the gate for the smaller organisms that lived in their shades to prosper as the niches have been left empty, so they quickly diversify and some of them manage to become the dominant ones, and the process continues. This happened with the sinapsids that dominated the Earth by died out because of mass extinction, the dinosaurs benefited from it so they became dominant while the mammals lived in their shades, then the dinosaurs had the same faith as the sinapsids, so the mammals took over.

Final answer:

Mass extinction events have been instrumental in animal evolution by causing rapid changes in biodiversity as new species evolve to fill empty niches. The most famous mass extinction, which led to the rise of mammals, was 65 million years ago. There have been at least five such events, with human activity potentially driving a current sixth period of mass extinction.

Explanation:

Mass extinction has played a significant role in animal evolution by radically altering the biological landscape. Whenever a mass extinction occurs, it acts as a reset button, eliminating dominant species and allowing for a sudden evolutionary burst as new species rush to fill the vacant ecological niches. This adaptive radiation can lead to increased biodiversity and the emergence of new groups of organisms. The most notable example of this process was the mass extinction event 65 million years ago, often associated with an asteroid impact, which led to the demise of the dinosaurs and opened the door for mammals, including our ancestors, to diversify and become dominant.

The Earth has experienced five mass extinctions that have been pivotal in shaping the course of evolution. Each of these events was caused by different factors, ranging from geological processes and volcanic activity to asteroid impacts and possibly human activities. The aftermath of these extinctions witnessed explosive diversification and evolution of lifeforms, drastically altering the composition and structure of ecosystems.

Human activities are now contributing to what some scientists consider the sixth mass extinction, known as the Holocene Extinction. The ongoing loss of species today is driven by habitat destruction, overexploitation, pollution, and climate change, which does not bode well for the future richness of evolutionary life forms as it did in earlier extinctions.

What horticultural method is used most often for vigorous rootstocks that do not produce good quality fruit or flowers?

layering
cutting
grafting

Answers

Answer:

grafting

Explanation:

When there's rootstocks that are vigorous, but they do not tend to produce fruits or flowers of good quality, then the most common method to solve the problem in the horticulture is the grafting method. The grafting is a method which is base around keeping the roots, but making clear diagonal cuts on the branches, and then attaching on those places small branches from a desired flower or fruit. Since the rootstock is strong and healthy, it will be an excellent basis for the growth of the fruits or the flowers. The newly attached, or rather grafted flower or fruit small branches will get the nutrients and water from the rootstock, so very quickly they will merge with it, thus becoming part of it. They will not produce the fruits or flowers that the rootstock originally produced, but instead they will produce the flowers or fruits of the rootstock from which they have been cut and grafted to the new one.

Grafting would be the answer

What is the ultimate source of genetic variation?

Answers

Answer:

mutations

Explanation:

Mutations are changes in DNA sequence that can create genetic variation within the population and thus are the ultimate source of new alleles . Mutations are important for evolution because of their ability to form a new genetic variant (allele) that can be spread to the offspring.  If a new variant of a trait formed by a mutation is advantageous and helps the organism to survive and reproduce,  it is going to be favourable by natural selection. That  variation will more likely be passed to the next generation and remain over time.

What do we mean when we say that the genetic code is degenerate?A single codon can encode more than one amino acid.An amino acid can be encoded by more than one codon.Codons are not always read correctly, resulting in the insertion of the wrong amino acid.A frameshift mutation usually results in abnormal protein.

Answers

Answer:

An amino acid can be encoded by more than one codon.

Explanation:

Codons are triplets of nucleotides in mRNA that are used for the protein synthesis (translation). A codon specifies a single amino acid, but there are exceptions. tRNA molecule contain anticodons, triplets of nucleotides that are complementary to codons. So, during the translation, tRNA carries the amino acid, that corresponds to the codon in mRNA.

Degenerate genetic code (more than one codon can code for the same amino acid) is important, because when point mutation occurs it is possible that the amino acid remains unchanged.

Final answer:

The genetic code is considered 'degenerate' because more than one codon can encode for the same amino acid. Despite this, the code is unambiguous - each codon uniquely specifies an amino acid. This feature helps reduce the negative impacts of random genetic mutations.

Explanation:

When we say that a genetic code is degenerate, we refer to the unique feature of the genetic code where multiple three-nucleotide sequences, or codons, can specify the same amino acid. In total, there are 64 possible codon combinations (4 nucleotide types to the power of 3 positions in the codon), but these only encode 20 amino acids and three stop codons. This means that some amino acids have more than one corresponding codon in the DNA and RNA alphabets.

For instance, let's take Amino Acid X. The codons UCU, UCC, UCA, and UCG could all code for Amino Acid X. This is what we mean when we say the genetic code is 'degenerate'. An important aspect here is that while the genetic code is degenerate, it is not ambiguous - each specific codon codes for one and only one amino acid.

Understanding this degeneracy is important because it reduces the negative impact of random mutations on protein synthesis. In other words, errors in the genetic code may still result in the correct or a similar-enough amino acid being produced, protecting the cell's ability to function correctly.

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Technician a says that the intake valve runs hotter than the exhaust valve because the intake valve has the greater surface area. technician b says that the exhaust valves usually do not burn due to the scavenging effect of the exhaust stream. who is right

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Technician B is correct, as exhaust valves usually run hotter due to direct exposure to combustion gases, despite the intake valve having a greater surface area. The intake valve is cooled by the fresh air-fuel mixture, resulting in lower temperatures.

The question discusses two technicians' perspectives on engine valve temperatures.

Technician A claims that the intake valve runs hotter because it has a greater surface area, while Technician B states that exhaust valves usually do not burn due to the scavenging effect of the exhaust stream.Technician B's assertion is more accurate. The exhaust valves generally experience higher temperatures because they are exposed to the hot combustion gases directly as the exhaust gases are expelled.

The intake valve, in contrast, is cooled to some extent by the fresh air-fuel mixture entering the cylinder. Therefore, despite having a greater surface area, the intake valve typically runs cooler than the exhaust valve.

The uterine phase where the thickness of the endometrium doubles is the

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Answer:

Proliferative phase

Explanation:

Uterine cycle is part of the menstrual cycle in which changes occur in the reproductve female system in order to prepare female on possible pregnacy. Uterine cycle isdivided into three phases:

Menstrual phase-characterized by the process of menstruationProliferative phase-estogen causes the production of new endomethrium layer (thickening of the endomethrium)Secretory phase-characterized by the production of progesteron which prepares endomethrium for the implementation.
Final answer:

The proliferative phase is when the endometrium doubles in thickness. This phase is stimulated by increased estrogen levels and prepares the uterus for potential pregnancy. If no fertilization occurs, this thickened lining is shed during menstruation.

Explanation:

During this phase, the granulosa and theca cells of the tertiary follicles begin to produce increased amounts of estrogen, stimulating the endometrial lining to rebuild. This phase occurs after menstrual flow ceases and is characterized by a thickening of the endometrium, the inner lining of the uterus, due to an increase in blood vessels and tissue in preparation for a potential pregnancy. If the egg is not fertilized, the corpus luteum degrades, leading to a decline in progesterone production and the shedding of the endometrium during menstruation.

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